3.11 Miscellaneous Instructions

The following instructions do not fit in any of the previous categories,
but are nonetheless useful.

3.11.1 Address Calculation Instruction

LEA (Load Effective Address)
transfers the offset of the source operand
(rather than its value) to the destination operand. The source operand must
be a memory operand, and the destination operand must be a general register.
This instruction is especially useful for initializing registers before the
execution of the string primitives (ESI, EDI) or the
XLAT instruction (EBX).
The
LEA
can perform any indexing or scaling that may be needed.
Example:

Causes the processor to place the address of the starting location of the
table labeled EBCDIC_TABLE into EBX.

3.11.2 No-Operation Instruction

NOP (No Operation)
occupies a byte of storage but affects nothing but the
instruction pointer, EIP.

3.11.3 Translate Instruction

XLAT (Translate) i
replaced a byte in the AL register with a byte from a
user-coded translation table. When
XLAT is executed, AL should have the
unsigned index to the table addressed by EBX.
XLAT changes the contents of
AL from table index to table entry. EBX is unchanged. The
XLAT instruction
is useful for translating from one coding system to another such as from
ASCII to EBCDIC. The translate table may be up to 256 bytes long. The
value placed in the AL register serves as an index to the location of the
corresponding translation value.